Internal combustion engine comprising at least one camshaft

ABSTRACT

An internal combustion engine, the engine having at least one camshaft, the camshaft is interconnected to the internal combustion engine through a plurality of rotating members, rotating members include at least one roller element and a predetermined load limit. The rotating members are configured individually along the camshaft and are positioned according to an actual internal combustion engine operating load value.

The present invention relates to an internal combustion engine comprising at least one camshaft.

Camshafts in internal combustion engines are part of a so-called valve train and are usually used to open and close intake and exhaust valves according to a design-determined valve timing. Such camshafts are usually mounted via so-called roller bearings which consist of at least one ring with rolling elements rotatably mounted therein. In order to be able to keep the variety of parts as low as possible, up to now, usually, identical bearings are used at all bearing positions of the camshaft which, however, is a disadvantage with respect to weight and cost because in this case, all bearings have to be designed for the maximally occurring loads.

The present invention is concerned with the problem of providing an improved embodiment for an internal combustion engine with a camshaft, which embodiment can in particular be implemented in a more cost-effective manner and with a lower weight.

This problem is solved according to the invention by the subject matter of the independent claim 1. Advantageous embodiments are subject matter of the dependent claims.

The present invention is based on the general idea not to use identical bearings at all bearing positions for mounting a camshaft in an internal combustion engine, as it has been the case up to now, but to embody the individual bearings individually and to adapt them in particular with respect to their bearing capacity to the loads actually occurring during the operation of the internal combustion engine at the respective bearing positions. For example, the loads for a bearing on a sprocket wheel of the camshaft are comparatively high, whereas the loads in the central region of the camshaft are often comparatively low. According to the invention, a bearing which is capable of withstanding a higher load or stress has now to be used in the region of the sprocket wheel, whereas in the region subjected to a lower load, a bearing can be used which, in comparison thereto, is lighter and in particular more cost-effective. Due to the individual adaptation of the individual bearings, in particular the total weight of all bearings used can be reduced which has an advantageous effect on the fuel consumption and therefore also on the CO₂ emission of the internal combustion engine. At the same time, the lighter bearings can be produced in a more cost-effective manner, whereby a reduction of the manufacturing costs can be achieved.

In an advantageous development of the solution according to the invention, a color marking is to be attached in each case on the camshaft and on the respective bearing, which color marking allows or simplifies associating the respective bearing with an assembly location on the camshaft. Since in contrast to the previously used and identically structured bearings it is now absolutely necessary for a problem-free operation of the camshaft to assemble the respective bearings correctly, in particular in the correct position, it must be reliably excluded during manufacturing that, for example, a light bearing is assembled in the region of a high load, for example in the region of a sprocket wheel, and wears out there comparatively quickly due the high loads and consequently has to be replaced quickly. The color markings on the camshaft and on the associated bearings make it easier for the assembler to correctly insert or correctly arrange the respective bearing so that the latter, for example, merely has to assemble a bearing marked in red at a position marked in red of the camshaft. By means of such a color marking, the error rate when assembling the bearings according to the invention can preferably be reduced to zero.

Further important features and advantages of the invention arise from the sub-claims, from the drawings, and from the associated description of the figures based on the drawings.

It is to be understood that the above mentioned features and the features yet to be explained hereinafter can be used not only in the respectively mentioned combination but also in other combinations or alone without departing from the context of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in the following description in more detail, wherein identical reference numbers refer to identical, or similar, or functionally identical components.

In the figures, schematically:

FIG. 1 shows a camshaft comprising two different bearings,

FIG. 2 shows a sectional view through different embodiments of bearings according to the invention.

According to FIG. 1, a camshaft 1 for an internal combustion engine, which otherwise is not shown here, has at least two bearings 2 and 2′ which, for example, can be configured as roller bearings and by means of which the camshaft 1 is mounted in the internal combustion engine. Also indicated are a cam 3 arranged on the camshaft 1 and a sprocket wheel 4 arranged at the end of the longitudinal side of the camshaft 1. According to the invention, the individual bearings 2, 2′ of which according to FIG. 1 only two are illustrated, are configured individually and are adapted with respect to their bearing capacity to the loads actually occurring at the respective bearing position. For example, in the region of the sprocket wheel 4, the load on the camshaft 1 is significantly higher than for example in a central region so that according to FIG. 1 and according to the invention, the bearing 2′ is configured to be stronger, higher loadable and also heavier than the bearing 2. Due to the individual and load-adapted configuration according to the invention of the individual bearings 2, 2′, it is no longer necessary to design all bearings for a maximum load as it has previously been the case when using identical bearings, but it is possible, in particular at positions of low load, to use lighter and/or more inexpensive bearings 2.

The individual bearings 2, 2′ can differ for example in a different number of rolling elements 5 as this is illustrated in case of the three exemplary illustrated bearings 2, 2′ in FIG. 2. The individual bearings 2, 2′ can also differ with respect to the diameters of the individual rolling elements 5, wherein according to FIG. 2, the rolling elements 5 of the bearing 2 drawn in the middle have a significantly smaller diameter than for example the rolling elements 5 of the bearing 2′ drawn in the illustration on the right. Moreover, depending on the expected load on the individual bearings 2, 2′—as mentioned above—it is also possible to provide a different number of rolling elements 5 so that for example the bearing 2 in the left illustration of FIG. 2 has significantly fewer rolling elements than the bearing 2 illustrated in the middle of FIG. 2.

Since up to now, identical bearings were assembled on the camshaft, it was not necessary to pay attention to a correctly positioned arrangement of the individual bearings at an assembly location on the camshaft 1. However, with the bearings 2, 2′ which, according to the invention, are configured individually, it is required for a problem-free operation of the camshaft 1 to arrange the different bearings 2, 2′ according to their bearing capacity in the correct position on the camshaft 1. For this purpose, color markings 6, 6′ which are attached according to the invention on the camshaft 1 and on a respective bearing 2, 2′ can be helpful and make it is easier to associate the respective bearing 2, 2′ with the assembly location on the camshaft 1. Thus, for example, a bearing marked in red can easily be associated with a red marked assembly location on the camshaft 1 so that an error rate during mounting or assembling the respective bearings 2, 2′ can be at least greatly reduced, preferably completely avoided.

With the bearings 2, 2′ which, according to the invention, are adapted individually and with respect to their bearing capacity to the loads on the camshaft 1 it is not only possible to use comparatively more cost-effective bearings 2, but it is in addition also possible to reduce the total weight of the bearings 2, 2′ which has a positive effect on the fuel consumption and the CO₂ emission of the internal combustion engine. 

1. An internal combustion engine, comprising: at least one camshaft, wherein the camshaft is mounted with a plurality of roller bearings, the roller bearings include at least one roller element and a predetermined roller bearing load limit, wherein the bearings are configured individually along the camshaft and are positioned according to an actual load value determined during the operation of the internal combustion engine.
 2. The internal combustion engine according to claim 1, wherein at least two bearings have a different number of rolling elements.
 3. The internal combustion engine according to claim 1, wherein at least two bearings have rolling elements, which are different with respect to their diameter.
 4. The internal combustion engine according to claim 2, wherein the rolling elements are needles.
 5. The internal combustion engine according to claim 1, wherein the camshaft and the at least one respective roller bearing includes at least one corresponding marking element, which provides an association between the roller bearing and assembly location of the actual load value of the camshaft.
 6. An internal combustion engine rotating assembly, comprising: at least one camshaft, the camshaft having a plurality of different operating loads; and at least two bearing elements configured on the camshaft, the bearing elements having at least one bearing capacity, each bearing capacity corresponding to the different operating loads of the camshaft, wherein the load bearing elements are configured about the camshaft adjacent at least one operating load, and wherein a bearing element diameter at a first predetermined position are different from the bearing elements at a second predetermined position.
 7. The rotating assembly according to claim 6, wherein a number of roller elements configured about the camshaft at the first predetermined position are different from a number of roller elements configured at the second predetermined position.
 8. The rotating assembly according to claim 6, wherein the rolling elements are needles.
 9. The rotating assembly according to claim 6, wherein roller elements are roller bearings that include at least on marking, the marking corresponds to a load marking on the camshaft, which provides an association between the roller bearing and an assembly location of the actual operating load value of the camshaft.
 10. A method of reducing weight in an internal combustion engine, comprising: selecting a first roller bearing with a plurality of roller elements, each roller element having a first diameter; selecting at least one additional roller bearing with a plurality of roller elements, each roller element having a different diameter from the first diameter; configuring the first roller bearing and the at least one additional roller bearing at predetermined positions on at least one camshaft; and implementing a configuring of an internal combustion engine with the least one camshaft.
 11. The method of claim 10, further comprising: determining an actual operating load along the length of the camshaft; and positioning at least one mark on the camshaft corresponding to the operating load.
 12. The method of claim 11, further comprising: determining a load capacity of each respective roller bearing, wherein the first and second roller bearings have different load capacities; comparing the actual load with the roller bearing load capacity; positioning at least one mark on at least one of the respective roller bearings, the roller bearing mark represents the predetermined load capacity and corresponds with the predetermined actual operating load; and positioning the roller bearing on the at least one camshaft, wherein the predetermined position corresponds to the markings on the at least one camshaft and roller bearing. 